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OC/GEO103 Lecture 5 Earth Structure

OC/GEO103 Lecture 5 Earth Structure. What’s inside the Earth? Is there really another world at the center? What is the energy for changing surface features?. The Earth System. Atmosphere. Hydrosphere. Atmosphere. Hydrosphere. Atmosphere. Cryosphere. Biosphere.

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OC/GEO103 Lecture 5 Earth Structure

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  1. OC/GEO103Lecture 5 Earth Structure

  2. What’s inside the Earth?Is there really another world at the center? What is the energy for changing surface features?

  3. The Earth System

  4. Atmosphere

  5. Hydrosphere Atmosphere

  6. Hydrosphere Atmosphere Cryosphere

  7. Biosphere Hydrosphere Atmosphere Cryosphere

  8. Lithosphere Biosphere Hydrosphere Atmosphere Cryosphere

  9. Our Dynamic Earth • Earth’s surface is constantly changing • How do we know it’s dynamic?? • Earthquakes (and tsunamis) • Volcanic eruptions • Magnetic Field • Surface Features: • Mountain Ranges; Mid-Ocean Ridges; Deep-Sea Trenches

  10. Topography of the Ocean Floor

  11. Topography of the Ocean Floor Mid-Ocean Ridge

  12. Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge

  13. Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge Island Chain

  14. Continents vs Oceans

  15. Elevated Continents

  16. Elevated Continents Submerged Ocean Basins

  17. How Big is the Earth? • Circumference  40,000 km (25,000 miles) • Radius  6,300 km (4,000 miles) • (1 meter = 1/10,000,000 distance from equator to pole)

  18. Major Questions: How are the ocean basins formed? How permanent are these features? What is the age of the ocean floor? What’s the age of the continents? Why are the ocean basins deep and the continents high?

  19. The Surface of the Earth • 2 levels: • elevated continents • submerged ocean basins • What causes these surface features? • We must know what goes on insidethe Earth

  20. What’s going on inside the Earth?

  21. Early Ideas • Jules Verne

  22. “Journey to the Center of the Earth” • Entered in Iceland • Exited in Italy

  23. Edgar Rice Burroughs • “Tarzan” • “John Carter of Mars”

  24. Pellucidar

  25. Pellucidar Fantasy!

  26. Earth’s Interior is: • Too hot! -- melted rock (magma) comes from even shallow depthsHeat comes from radioactivity (principally K, U and Th in the mantle) • Crushingly high pressure! -- no open spaces!

  27. Information about the Earth’s Interior comes from: • Volcanoes • Seismic Waves (“sound images”) • Meteorites

  28. Volcanoes • Hawaiian “hotspot” etc • Windows into theEarth • Samples 200km down(e.g., diamonds!)

  29. Seismic Waves • Sound energyfrom earthquakesand large explosions is recorded at seismometers distributed around the globe

  30. Meteor Crater (Arizona)

  31. Willamette Meteorite • Found 1902,in West Linn • Largest inthe U.S.A. • Sold and nowresides at the American Museum of Natural History, in NYC

  32. Dimensions and Boundaries • Top of Mantle • 10 to 70 km (5 to 30 miles) • Top of Core • 2,900 km (2000 miles) • Center of Earth • 6,300 km (4,000 miles) • Mt. Everest  9 km high. • Mariana Trench 11 km deep.

  33. Where does this picture come from?Direct Observations: • Exposures on Surface • Up from  50 km (30 miles) depth • Drilling • To  15 km (10 miles) • Volcanic Material • Up from  200 km (120 miles) depth

  34. Indirect Observations: • Magnetic Field => Iron core • Gravity Field • Densities: • Crust: 2 - 3 gm/cm3 • Mantle: 3.3 - 5.8 gm/cm3 • Core: 10.8 gm/cm3 • Earthquake Seismic Waves => Physical state of crust, mantle, core.

  35. Interior of Earth by STRENGTH • LITHOSPHERE • rigid outer shell • crust and upper mantle (~ 50 to 200 km thick) • somewhat brittle, breakable • cold (likebutterout of fridge) • ASTHENOSPHERE • warmer, plastic layer under lithosphere • mantle from ~ 150 to 700 km • squishy, plastic • warm (like softened butter) • LOWER MANTLE • Solid, but can flow over time! • ~700 to 2900 km • OUTER CORE • liquid • INNER CORE • solid

  36. Elevated Continents Submerged Ocean Basins

  37. Swimming Pool

  38. Earth’s Mantle

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